Worst case: Those very few and low-level spurious signals of the “Discovery” disappear completely in the atmospheric noise after you connect an antenna – leaving even faintest stations in the clear.

There had been some discussion about the “real” performance of the brand new Airspy HF+ “Discovery”. It is not only my experience that this great little SDR is a perfect performer at a ridiculous low price.

The discussion focuses on “spurious signals”. I measured them with the Winradio SIGMA as spectrum analyzer, compared it to the two past Airspy HF+ models, plus Discovery, and did some work on how this effect might touch reception.

The result is clear: this discussion in the Ivory Tower is “Much Ado about Nothing”. You may read more about method & findings, with many diagrams, in this PDF.

Morse Code or CW has become rare among professionals (in the West). But there is a busy net of small Japanese Fishery Stations literally pounding the brass. One of them is Kagoshima Radio, JFX. They are not daily heard in Europe, but a combination of receiver Winradio Sigma, active antenna MD300DX (2×2.5 m, vertical) and SDRC V3 software did the trick even under this grim summer propagation. See screenshot above, from 24 hours’ recording of 25 MHz HF. All channels clearly readable – as far as the expressive handwriting (see detailed screenshot at the bottom) of their CW allows for … Yeah: CQ CQ DE JFX JFX QRU QSX 6 / 8 /12 MHz K

First part of the CQ call of JFX in good ol’ hand-made CW … from 12704.5 kHz

A big achievement: The new Airspy HF+ “Discovery” is even smaller than the Airspy HF+.

From start, Airspy SDRs with their unique block diagram received an overwhelming reputation in the challenging HF bands. They feature a high dynamic range in a small case – and even match a small wallet, too. Now their new “Discovery” enters new dimensions in every respect. The photo on top shows the small black beauty in the foreground compared to the already known Airspy HF+ in the background.

It is already running here with e.g. SDR# and SDRC V3 software, see below. The very first impression is that of an SDR with an exceptionally low noise level and, thanks to its tracking filters, a matching dynamic range. Alas, being a bit short in time these days, I hope to come back with some more solid comments in due time.-

A first look onto the 19m broadcast band shows the low noise level plus the high sensitivity, resulting in a great SNR.

Specified to receive already from 0.5 kHz, it is a true performer also on VLF – see screenshot below with reception of US Navy Cutler/Maine on 24 kHz, about 35 dB down of Germany powerhouse DHO38 just 600 Hz below. Reception: August 2nd, 2019, 14:38 UTC in Germany with vertical active dipole (2×2.5 m) MD300DX.

Fine VLF reception of MSK signal MIL-STD-188-140 from US Navy in Cutler/Maine on 24 kHz. Horizontal lines are from thunderstorms, and the “hill” peaking near 34.5 kHz is local noise.

Part of a multi-channel monitoring of the HFGCS net in ALE on July 14, 2019: the vertikal axis shows the channel, the horizontal axis the time of monitoring.

2019 is the year of groundbreaking Software-defined radios, covering the whole HF range of 30 MHz width and recording it for many hours, e.g. from midnight to midnight. In combination with proper software, this allows for a fresh view onto monitoring.

For the screenshot on the top, I had monitored nine HFGCS channels from 3137 kHz to 23327 kHz in parallel (the 18003 kHz didn’t work, sorry) with Winradio’s SIGMA SDR, running with Simon Brown’s free software SDRC V3 and nine instances of MultiPSK decoder.

After automatic monitoring, I harvested all time-stamped logs stripped them from information not needed, and imported them to free Tableau Public software to visualize activity according to station, time and channel. This gives an overview on the monitoring session, propagation, time sequences of hopping from channel to channel etc. – you might zoom into the screenshot for a clearer look.

Thanks to Tableaus also stunning geospatial features, completely other views of the same log are available. The screenshot below shows the number of logs on all channels of a monitoring session of 12 hours.

Geospatial information of the stations, combined with the number of log entries on all channels.

You may zoom into this OSM[ap], and you may also have a zoomed satellite view (or this or that) which directly hits the feeder point of your antenna … if you know the exact location and this is a part of your log entry – see screenshot below.

Zooming the map above onto JDG at satellite view, directly leads you to the location of the station – here Diega Garcia US Military base.

The most versatile Tableau software also allows to relaize many other ideas to visualize monitoring; some of them already above horizon, others still below. To conclude this entry, I did a visualization of all HF stations/channels of AFAD, the Turkish Disaster and Emergency Management Authority, heard by me over the last 18 months. Each (?) of the 81 Turkish provinces maintains an AFAD base, and all (most?) of them are communicating on HF. As Tableau has many detailed geographical already aboard, a visualization of channels/province being heard is easy.

Analyzing part of a logbook: All Turkish provinces heard with ALE signals of AFAD are colored – the deeper the color, the more channels were received in the last 18 months.

All main six GMDSS channels on HF at once: Winradio’s SIGMA with Simon Brown’s software SDRC V3

Some days ago, I wrote about my very first experiences with Winradio’s groundbreaking SIGMA SDR receiver, covering e.g. the whole HF band with 32 MHz width and 16 bit resolution – plus much, much more. SIGMA comes with a fine software, and provides an API.dll for connection to 3rd-party software. Thankfully, Simon Brown, G4ELI, adapted his unique SDRC V3 software to this (and other) Winradio in nearly no time.

This combination has become a real dream team: the best hardware and the best software avalaible. The screenshot at the top shows just one example of others which will follow: I made a 24 hour recording of 0 to 25 MHz (7.85TB) and placed six demodulators on the main GMDSS channels on HF between 2 and 16 MHz. You see each channel in a separate window at the top of the screenshot, showing spectrum and spectrogram with time stamps of the recording. Below those six channels you see spectrum and spectrogram of the whole recorded bandwidth, namely 25 MHz. Eventually, below this spectrogram you see 60 x 24 boxes, one for every minute of the 24 hours recording. Just click into the time you want, and the recording instantaneoulsy to it.

Demodulated audio is guided via VAC1 … VAC6 to six different instances of the free YAND GMDSS decoder – see screenshot at the bottom.

There are great many other applications of this revolutionary combination to which I will come back later.

The new Redpitaya (RP-16) has arrived here, see photo gallery at the bottom. With now 16 bit and a largely improved input section, it promises to match amateur’s and SWL’s needs for an able SDR transceiver or receiver even better than its predecessors with 12 and 14 bit.

My initial idea was to get a nice, fool-proof, competetive SDR with up to 30 MHz bandwidth for just around 450$. However, from start, the RP-16 seems to test more me than vice versa. First, me and a most capable friend didn’t get it going at all. Here, secondly, Joerg, DD8JM, stepped in and did wonders with the Micro card from which the RP-16 has to read its software after sniffing power. It turned out that the card had two partitions and three software versions on the card – which you cannot see with Windows od Mac OS, but with Linux only. And RP didn’t liked that. Thankfully, Jörg tided up the card, and it worked – at least over a router.

The only SDR software available at early July 2019 seems to be openHPSDR. So, over a modem it all worked in general, see screenshot at top. But there were annoying audio drops and occasional overdrive from strong signals – despite an extra 30 MHz low-pass filter from Heros and bright daytime.

Despite having worked on this for many hours, I am still not quite sure who is testing whom. At least so far, my test of the new Redpitaya was disappointing. Maybe it will live up to my expectations under another software, namely Simon Brown’s (G4ELI) SDRC. I will see, because with 69g only, it doesn’t make an ideal paperweight …

If you made different experiences, tell me! I would be more than pleased to jump in and spread such welcomed news.

When I saw the late Chuck Berry in concert with Jerry Lee Lewis, the latter was announced as: “… the killer speaking!” Having switched on Winradio’s WR-G65DDCe, or ‘Excalibur Sigma’, the also breathtaking show of this receiver reminds me to that concert: The Sigma is also kind of a killer to all other software-defined radio (SDRs) for which it now defines the benchmark in nearly all aspects.

It comes as the top model of a highly respected line of SDRs from Winradio in Australia, which pioneered the market of high performance receivers defining the state of the art. For hobbyists, the Winradios often define the utmost price tag they want to pay. Whereas professionals, in opposite, are happy to get an excellent peformance at modest costs. Yes, buying the Sigma will set you back nearly 7’000 Euros, but: “Madame, there is no second.”

What makes the Sigma unique? First, it is its covering up to 64 MHz with 16 bit resolution flawlessly over an USB3.0 connection, resulting in a spurious-free dynamic range of 111 dB (2 dB lighter with pre-amplifier). You may record this full range even onto external hard disk without loosing a bit. Then you may play back and tune it as live from the hard disk, offline and flawlessly. The whole HF range from 0 to 32 MHz needs about 155 MB/s with even some headroom when doubling the range to even 64 MHz. Winradio says, the Sigma will run from a quad core, and they are right: I have it running from a laptop Dell Inspiro 5770 with i7 8550U @1.8 GH, 4 cores, 16 GB RAM, 2TB hard disk. CPU usage during recording a 32 MHz wide range was never over around 12%.

From start, Winradio has built up a solid reputation to combine professional hardware delivering top performance with intuitive software, resulting in a nearly unsurpassed user experience. As you can rely on the published data, I want to concentrate on Sigma’s practice. This will be a work in progress as it should include some time-consuming recordings and comparisons.

P.S. UK’s „Radiouser“ and Germany‘s „Funkamateur“ will publish an in-depth article on the Sigma in their September issues. Stay tuned.